I used an exede on my Subaru for a while but it had some "issues" that they were unable to fully resolve, despite being actively involved with the vehicle. Ultimately I had to use another solution. To be fair I have heard generally good things about them and they were one of the first to develop a plug and play unit for the 335I. I think the cost was around $1600 but I stand to be corrected. Check their website at
www.exede,com.au